/Engine/Source/Runtime/GeometryCore/Public/DynamicMesh/MeshTangents.h
Return tangent and bitangent at a vertex of triangle for per-triangle computed tangents
void GetPerTriangleTangent ( int32 TriangleID, int32 TriVertIdx, [UE::Math::TVector](API\Runtime\Core\Math\TVector)< RealType > & TangentOut, [UE::Math::TVector](API\Runtime\Core\Math\TVector)< RealType > & BitangentOut ) const